A fast and reliable perturb and observe maximum power point tracker for solar PV system

摘要

Solar energy is considered as the most reliable among all renewable energy sources. Solar photovoltaic (PV) is used to convert solar energy into unregulated electrical energy. Maximum power point tracker (MPPT) is used to harness maximum power from solar PV due to its non linear characteristics and low efficiency. Perturb and observe (P&O) is one of the MPPT method used in solar PV system. The conventional P&O MPPT method has the drawback of low convergence time and steady state oscillation with fix step size. In this paper a modified P&O method is designed to achieve high convergence speed and low oscillations. The new method also assures reliable operation under fast changing atmospheric conditions and under load variations as well. A prototype unit is made in the lab and tested for improved results. Simulation study is done using PSIM simulation software. The proposed P&O MPPT is tested with resistive load connected to DC bus and with commonly used compact fluorescent lamp (CFL) load after connecting high frequency inverter between DC bus and CFL. The improved P&O MPPT scheme gives convergence time of 0.1 s, steady state oscillations in power is 1 W and time to restore maximum power point during load change condition is 0.15 s.